Coated articles and IG window units are known which use the following coating: glass/SiN/NiCr/Ag/NiCr/SiN. For example, see U.S. Pat. Nos. 6,605,358, 6,730,352 and 6,802,943, the disclosures of which are hereby incorporated herein by reference. While these coated articles provide for good results in many applications, their color characteristics are sometimes not desired.
In particular, a fairly strong blue color (e.g., glass side reflective color) is sometimes desired. Typical glass/SiN/NiCr/Ag/NiCr/SiN coated articles do not provide such strong blue glass side coloration along with desired solar characteristics. For example, prior to heat treatment, Example 1 of U.S. Pat. No. 6,605,358 having a stack of glass/SiN/NiCrN/Ag/NiCrN/SiN realized a glass side reflective a* color of −0.96 and a glass side reflective b* color of −7.92. These color values slightly change upon heat treatment (HT). Unfortunately, the b* value of −7.92 is not blue enough for certain applications.
In view of the above, it will be appreciated that there is a need in the art for a coated article that is capable of realizing a combination of good solar control characteristics and desired blue color (e.g., glass side reflective color).
In certain example embodiments of this invention, it has surprisingly been found that a desirable blue color can be realized, in combination with good solar characteristics, by adjusting thicknesses of layer(s) in the coating.
In certain example embodiments of this invention, a coating is provided that realizes glass side reflective b* coloration of from about −15 to −25, more preferably from about −16 to −23 (before and/or after optional heat treatment), in combination with glass side reflective a* coloration of from about −4 to +4, more preferably from about −2 to +2. Good solar control characteristics (e.g., fairly low sheet resistance and/or emissivity) can also be achieved. The combination of these desirable features may be realized by thickening the lower dielectric layer in certain example embodiments of this invention, while possibly providing a thicker upper dielectric layer in certain example instances.
Coated articles according to certain example embodiments of this invention may be used in the context of insulating glass (IG) window units, monolithic windows, or in other suitable applications in different instances.
In certain example non-limiting embodiments of this invention, a coated article is provided having a stack of glass/SiN/NiCr/Ag/NiCr/SiN, where the bottom silicon nitride inclusive layer has a thickness of from about 72.5 to 110 nm, more preferably from about 80–95 nm. The top silicon nitride inclusive layer may have a thickness of from about 30–70 nm, more preferably from about 48–65 nm. These thickness ranges used in combination allow for desirable significantly blue coloration to be realized in certain example embodiments of this invention.
In certain example embodiments of this invention, there is provided a coated article including a multi-layer coating supported by a glass substrate, the coating comprising at least the following layers from the glass substrate outwardly: a first layer comprising silicon nitride; a first contact layer comprising Ni and/or Cr; an infrared (IR) reflecting layer comprising silver located over and directly contacting the first contact layer comprising Ni and/or Cr; a second contact layer comprising Ni and/or Cr located over and directly contacting the IR reflecting layer; a second layer comprising silicon nitride on the glass substrate located over at least the IR reflecting layer, the contact layers and the first layer comprising silicon nitride; and wherein the first layer comprising silicon nitride is from about 72.5 to 110 nm thick, and wherein the coated article has the following glass side reflective color values: a* from −4 to +4, and b* from −15 to −25.
In other example embodiments of this invention, there is provided a coated article including a multi-layer coating supported by a glass substrate, the coating comprising at least the following layers from the glass substrate outwardly: a first layer comprising silicon nitride; a first contact layer; an infrared (IR) reflecting layer located over and directly contacting the first contact layer; a second contact layer located over and directly contacting the IR reflecting layer; a dielectric layer; wherein the first layer comprising silicon nitride is from about 72.5 to 110 nm thick, and wherein the coated article has the following glass side reflective color values: a* from −4 to +4, and b* from −15 to −25.